NAME

SYNOPSIS

The
diffmk
command compares two versions of a file
and creates a new file that marks the differences.

OPTIONS

Uses
mark
to mark where added lines
begin.
Uses
mark
to mark where added lines
end.
Ignores differences that are only changes in tabs or spaces
on a line.
Uses
mark
to mark where changed
lines begin.
Uses
mark
to mark where changed
lines end.
Uses
mark
to mark where deleted
lines begin.
Uses
mark
to mark where deleted
lines end.

DESCRIPTION

The
file1
and
file2
variables are the old and new versions of the file, respectively. The
diffmk
command compares them and writes a new version to standard
output, which can be redirected to a file. This output contains the lines
of
file2
marked with
nroff
change
mark requests (.mc), or with the
marks
you specify with the
-ab,
-ae,
-cb,
-ce,
-db, and
-de
options.

When output containing
.mc
requests is formatted
with
nroff, changed or inserted lines are marked by a
|
(vertical bar) at the right margin of each line. An
*
(asterisk) indicates that a line was deleted.

If the
DIFFMARK
environment
variable is defined, it names a command string that
diffmk
uses to compare the files. (Normally,
diffmk
uses the
diff
command.) For example, you might set
DIFFMARK
to
diff
-h
in order
to better handle extremely large files.

EXAMPLES

This causes
diffmk
to create a copy of
chap1
called
chap1.diffs, showing differences
between
chap1.old
and
chap1. Additions
of one or more lines are marked with
>I
and
<I, changed lines are marked with
>C
and
<C, and deletions are marked with
>D
and
<D.
To mark differences with
nroff
requests,
enter:
diffmk chap1.old chap1 > chap1.nroff

This produces a copy of
chap1
called
chap1.nroff
containing
nroff
change mark requests
to identify text that was added to, changed, or deleted from
chap1.old.
To use different
nroff
marking requests
and ignore changes in white space, enter:
diffmk -b -cb'.mc %' chap1.old chap1 > chap1.nroff

This imbeds commands that mark changes with
%
(percent
sign), additions with
|
(the default, because no
-a
option is specified), and deletions with
*
(the
default). It does not mark changes that only involve a different number of
spaces or tabs between words (-b).